Method of controlling the release of agricultural active ingredients from treated plant seeds

ABSTRACT

A method of controlling the release rate of an agricultural active ingredient from a seed that has been treated with that active includes providing a seed that has been treated with the active ingredient, applying to the treated seed a film that includes an emulsion of a polymer in a liquid in which both the agricultural active ingredient and the polymer have low levels of solubility, and then curing the film to form a water insoluble polymer coating on the surface of the treated seed. Seeds that have been treated by this method are also provided.

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 60/277,503 filed Mar. 21, 2001, which isincorporated herein by reference thereto.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methods for controlling the release ofagricultural active ingredients from treated plant seeds, and moreparticularly to methods for controlling the release of agriculturalactive ingredients from treated plant seeds by the use of seed coatings.

2. Description of Related Art

The development and use of pesticides has increased the yield of mostagronomically important plants. Pesticides, including herbicides,insecticides, nematocides, acaracides, fungicides, bactericides, and thelike, are now widely applied to soils prior to, during, or after seedplanting, or are applied directly or indirectly to growing plants atvarious times during the growing season.

Widespread use of pesticides has not been without problems, however, dueto the wide spectrum of activity and high toxicity of some pesticides.Such negative results have been exacerbated by the widespreaddistribution of pesticides in the environment through such vectors asrunoff, wind-drift, leaching, animal activity and the like. This type ofmovement of pesticides away their point of application and target ofactivity also requires that higher levels of the pesticide be used inorder to insure that the application provides the desired pesticidalactivity for the desired period of time that it is required.

One method that has been found to be promising in some applications isthe treatment of plant seeds with pesticides. General information onthis subject is provided in, for example, Chemtech, 8.284-287 (May1978). In situations where seed treatment is effective, it can reducethe amount of pesticide that is required to obtain a desired level ofactivity. Other advantages of direct, pre-planting seed treatmentinclude reducing the number of separate field passes that a farmer mustmake to prepare for, plant, and raise a crop, and limiting at least theinitial zone of pesticidal activity to the seed and its immediateenvironment. Further information about seed coatings has been publishedby Barke et al., who describe seed coating compositions comprising astabilizing polyol in U.S. Pat. No. 4,272,417. Seed coatings containingpolyelectrolyte complexes are disclosed by Dannelly in U.S. Pat. No.4,245,432. Kouno has described a method of applying gel coating to seedsin U.S. Pat. No. 4,808,430. In U.S. Pat. No. 4,735,015, Schmolka hasdescribed enveloping a seed in a coating containing certainpolyoxyethylene-polyoxybutylene block copolymers.

Early seed treatment applications were often carried out by simplyapplying a pesticide—a fungicide, for example—directly to a seed,followed by drying the treated seed for storage and use. It was soonapparent, however, that this technique also had drawbacks, such astoxicity of the pesticide to the seed, high rates of loss of thepesticide during storage and the exposure of workers handling andplanting the seed to high levels of the pesticide. In cases where thepesticide was water soluble or easily leached from the seed, the loss ofpesticide from the zone of the seed could be rapid. Not only could thisreduce the efficacy of the treatment, but could also cause unwantedrelease of the pesticide into the environment.

In many cases, it is desirable to retard or control the release of theactive from the seed because of safety considerations and to increasethe efficiency of use of the active. For example, if release of apesticide can be controlled so that the concentration of the pesticidein the zone of the seed reaches and remains at an effective level duringthe time the target pest is active, the efficiency of use of thepesticide is increased over what would ordinarily be expected if thepesticide was merely applied to the soil at planting. Examples ofmethods to control the release of actives by the use of seed coatingshave been described by, among others, Turnblad et al. in U.S. Pat. Nos.5,849,320 and 5,876,739, who disclosed insecticidal coatings comprisinga polymer binder, an insecticide and a filler, where the binder formed amatrix for the insecticide and the filler. Application of such a coatingto a seed and the optional subsequent application of a protectivepolymer overcoating were also described.

One of the considerations of including a pesticide, such as aninsecticide, in the seed coating itself is that the active agent ispresent throughout the coating and even on the outer surface of thecoated seed. This permits anyone handling the seed to contact the activeingredient directly. In order to minimize this contact, it is necessaryto add a second, additional, coating to the seed. This requiresadditional materials and results in higher cost of seed preparation.

Another problem that has hindered the development of seed coatings thatcontrol the release of pesticides has been the requirement for coatingsthat are carefully tailored to provide a certain chemical relationshipwith the pesticide. For example, the combination of the pesticide andthe coating must meet certain criteria of release rate, protection ofthe active, protection of the seed, and the like, while not binding thepesticide so tightly that release is prevented entirely. The developmentof coating formulations that meet these criteria has routinely takensignificant time and effort, and the formulations are most often limitedto use with one type of pesticide.

Accordingly, it would be useful to devise a method for controlling therelease of agricultural actives from a seed that has been treated withsuch actives where the methods are easy, fast and economical toadminister, and are effective in controlling the release of the activefrom the treated seed. Moreover, it would be useful if such methodscould be used with a wide range of agricultural actives and if theycould be practiced without the inconvenience and expense of having todevelop a polymer coating having certain chemical compatibility betweena particular active and the polymer.

SUMMARY OF THE INVENTION

Briefly, therefore, the present invention is directed to a novel methodof controlling the release rate of an agricultural active ingredientfrom a seed treated with the active ingredient, the method comprisingthe steps of: providing a seed that has been treated with anagricultural active ingredient; applying to the treated seed a filmcomprising an emulsion of a polymer in a liquid in which both theagricultural active ingredient and the polymer have low levels ofsolubility; and curing the film to form a water insoluble polymercoating on the surface of the treated seed.

The present invention is also directed to a novel treated seed that iscoated by the method described above.

The present invention is also direct to a novel method of protection ofa seed comprising treating the seed by the method described above.

Among the several advantages found to be achieved by the presentinvention, therefore, may be noted the provision of a method ofcontrolling the release rate of an agricultural active ingredient from aseed treated with the active ingredient, where the method is easy, fastand economical to administer; the provision of such a method that iseffective in controlling the release of the active from the treatedseed; the provision of such a method that can be used with a wide rangeof agricultural actives; and the provision of such a method that can bepracticed without the inconvenience and expense of having to develop apolymer coating having certain chemical compatibility between aparticular active and the polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the release of imidacloprid as a function of time from cornseed that had been treated with imidacloprid followed by no overcoating,or overcoating according to an embodiment of the subject method with anemulsion containing Aquacoat ECD, Surelease Polymer, Stepan NMS Latexwith T_(g)=25° C., or Stepan NMS Latex with T_(g)=15° C.;

FIG. 2 shows the release of imidacloprid as a function of time fromcotton seed that had been treated with imidacloprid followed by noovercoating, or overcoating according to an embodiment of the subjectmethod with an emulsion containing Stepan NMS Latex; and

FIG. 3 shows the release of tebuconazole as a function of time from cornseed that had been treated with tebuconazole followed by no overcoating,or overcoating according to an embodiment of the subject method with anemulsion containing Stepan NMS Latex with T_(g)=15° C., or Stepan NMSLatex with T_(g)=25° C.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, it has been discovered thatthe release rate of an agricultural active ingredient from a seed thathas been treated with such active can be controlled by applying to thetreated seed a film of an emulsion of a polymer in a liquid in whichboth the agricultural active ingredient and the polymer have low levelsof solubility, and then curing the film to form a water insolublepolymer coating on the surface of the treated seed.

This method has been found to be an effective way to provide seeds thathave been treated with, for example, a pesticide, that have a controlledrelease rate of the pesticide into the environment around the plantedseed, thereby increasing the efficiency of the pesticide. Moreover, thepolymer coating is easy and economical to apply to the seeds, and theapplication can be done in the same equipment in which the seeds aretreated with pesticide. Unlike conventional methods of formingcontrolled release compositions, the novel method provides theunexpected advantage that the polymer that is used to form the coatingdoes not necessarily have to have any particular chemical compatibilitywith the active ingredient. Therefore, the method is believed to beespecially useful for seeds that have been treated with two or moreactive ingredients that have chemical characteristics that aresignificantly different from each other. Such a combination of activeswould normally make it difficult, if not impossible, to design a typicalcontrolled-release formulation having desirable release characteristicsfor both active ingredients.

It is believed that another surprising property of the novel method isthat it results in treated seed having a single coating that has verylow levels of the active ingredient at the outer surface of the coating.This is thought to remove the need for the application of a separateovercoating of the seed, while providing a treated seed that is safer tohandle and provides greater control of the active than an uncoated seed.

Polymers that can be used to form the present coating are those that arecapable of forming a water insoluble coating upon curing. When it issaid that the coating is a water insoluble, it is meant is that thecoating has a water solubility of less than about 1%, and preferablyless than about 0.1%, by weight, at 25° C. Among the advantages that acoating having low water solubility provides is that the loss of thecoating due to water solubilization in the environment is reduced. It isalso preferred that the polymer is one that is non-toxic to the seed towhich it is to be applied, i.e., that it is non-phytotoxic.

Polymers that are suitable for use in the present method can bepolyesters, polycarbonates, co-polymers of styrene, and mixturesthereof. Examples of preferred polymers areacrylonitrile-butadiene-styrene terpolymer (ABS); ABS modifiedpolyvinylchloride; ABS-polycarbonate blends; acrylic resins andco-polymers: poly(methacrylate), poly(ethylmethacrylate),poly(methylmethacrylate), methylmethacrylate or ethylmethacrylatecopolymers with other unsaturated monomers; casein; cellulosic polymers:ethyl cellulose, cellulose acetate, cellulose acetatebutyrate; ethylenevinyl acetate polymers and copolymers; poly(ethylene glycol);poly(vinylpyrrolidone); acetylated mono-, di-, and triglycerides;poly(phosphazene); chlorinated natural rubber; polybutadiene;polyurethane; vinylidene chloride polymers and copolymers;styrene-butadiene copolymers; styrene-acrylic copolymers;alkylvinylether polymers and copolymers; cellulose acetate phthalates;epoxies; ethylene copolymers: ethylene-vinyl acetate-methacrylic acid,ethylene-acrylic acid copolymers; methylpentene polymers; modifiedphenylene oxides; polyamides; melamine formaldehydes;phenolformaldehydes; phenolic resins; poly(orthoesters);poly(cyanoacrylates); polydioxanone; polycarbonates; polyesters;polystyrene; polystyrene copolymers: poly(styrene-co maleic anhydride);urea-formaldehyde; urethanes; vinyl resins: vinyl chloride-vinyl acetatecopolymers, polyvinyl chloride and mixtures of two or more of these.

The polymers derived from unsaturated amine salts that are described inWO 98/32726, WO 98/32773, WO 00/05950, WO 00/06612, and WO 00/06611, tothe Stepan Company, are preferred. More preferred are the polymers thatare known commercially as NMS Latex polymers (Stepan Company).

Polymers that are biodegradable are also useful in the presentinvention. As used herein, a polymer is biodegradable if is not watersoluble, but is degraded over a period of several weeks when placed inan application environment. Examples of biodegradable polymers that areuseful in the present method include biodegradable polyesters;starch-polyester alloys; starch; starch-PCL blends; polylactic acid(PLA)-starch blends; polylactic acid; poly(lactic acid-glycolic acid)copolymers; PCL; cellulose esters; cellulose acetate butyrate; starchesters; starch ester-aliphatic polyester blends; modified corn starch;polycaprolactone; poly(n-amylmethacrylate); ethyl cellulose; wood rosin;polyanhydrides; polyvinylalcohol (PVOH); polyhydroxybutyrate-valerate(PHBV); biodegradable aliphatic polyesters; and polyhydroxybutyrate(PHB). A biodegradable aliphatic polyester such as BIONOLLE, from ShowaHigh Polymer, Tokyo, Japan, is preferred.

The polymer emulsion of the present method can also include anon-migrating surfactant. When it is said that the surfactant is“non-migrating”, it is meant that the surfactant is substantiallyinsoluble in water and, if the liquid used to form the polymer emulsionis other than water, then the surfactant is also substantially insolublein that liquid. When it is said that the surfactant is “substantiallyinsoluble”, it is meant that it has a solubility in a particular liquidat 25° C. of less than about 1% by weight, preferably of less than about0.1% by weight, and more preferably of less than about 0.01% by weight.

The non-migrating surfactant can also be a molecule that is bound to thepolymer that is described above, rather than being a separate entity.Such binding can be in the nature of a chemical bond, or it can be inthe nature of an ionic attraction.

Non-migrating surfactants that are useful in the present method aredisclosed by Guyot, A., in Current Opinions in Colloid and SurfaceScience, pp. 580-585 (1996); Guyot, A. et al., in Advances in PolymerScience, 11, 43-65, Springer-Verlag, Berlin (1994); and by Holmberg, K.,in Progress in Organic Coatings, 20.325-337 (1992). Preferrednon-migrating surfactants are described in WO 00/05950, and includediallyl amine pluronics (available from BASF), linoleic alcoholderivatives (available from ICI), allyl alkyl phenol derivatives(available from DKS, Japan), acrylate derivatives (available from PPG),allyl alcohol alkenyl succinic anhydride derivatives (available fromKAO, Japan), Polystep RA series (maleic derivatives, available fromStepan Co.), maleic derivatives (available from Rhone Poulenc), and TremLF-40 allyl slufosuccinate derivatives (available from Henkel).

It is believed that the use of a surfactant having the characteristicsdescribed above provides the benefits of (1) permitting control ofpermeability of the coating, which modulates the release rate of theactive through the coating and also controls the rate of waterpermeation from the soil into the seed; and (2) remaining with thepolymer while in liquid emulsion form; and (3) the surfactant is notlost from the coating by contact with water after planting. The coatingpermeability is related to the glass transition temperature of thepolymer/surfactant mix (T_(g),), and this parameter can be used as anindicator of the degree of permeability of the coating.

In a preferred embodiment of the invention, the water insoluble polymerand the non-migrating surfactant and the relative amounts of each areselected so that the polymer coating that is formed from the waterinsoluble polymer and the non-migrating surfactant has a glasstransition temperature within a pre-selected range, thereby providing acoating which retards the release rate of the agricultural activeingredient from the seed by a desired amount. The glass transitiontemperature of the polymer coating can be within the range of from about−5° C. to about 75° C. It is preferred, however that the glasstransition temperature of the polymer coating is within the range offrom about 10° C. to about 50° C., more preferred that the glasstransition temperature of the polymer coating is within the range offrom about 15° C. to about 40° C., and even more preferred that theglass transition temperature of the polymer coating is within the rangeof from about 15° C. to about 25° C.

It is believed that the subject method can be used on the seed of anyplant. However, it is preferably used on seeds of plant species that areagronomically important. In particular, the seeds can be of corn,peanut, canola/rapeseed, soybean, curcubits, cotton, rice, sorghum,sugar beet, wheat, barley, rye, sunflower, tomato, sugarcane, tobacco,oats, was well as other vegetable and leaf crops. It is preferred thatthe seed be corn, soybeans, or cotton seed, and more preferred that theseed be corn.

Seeds on which the present invention can be used can be seeds that donot have a transgenic event, or can be transgenic seeds.

Although the present method can be applied to a seed at any state ofdevelopment, it is preferred that the method is applied after the seedhas been harvested and before the seed has been planted. It is alsopreferred that the subject method be applied to a seed that has beendried to a moisture level that is suitable for stable storage.

The subject method can be used to control the release of almost any typeof agricultural active ingredient that has been applied to a seed. Forexample, the active can be a growth factor, a growth regulator, apesticide, or the like. If the active is a pesticide, such pesticide canbe selected from herbicides, molluscicides, insecticides, nematocides,acaricides, fungicides, bactericides, and the like. Although the subjectmethod can be used for seeds that have been treated with only oneactive, it is also useful for seeds that have been treated by two ormore active ingredients.

Pesticides suitable for use in the invention include pyrethrins andsynthetic pyrethroids; azoles, oxadizine derivatives; chloronicotinyls;nitroguanidine derivatives; triazoles; organophosphates; pyrrols;pyrazoles; phenyl pyrazoles; diacylhydrazines; biological/fermentationproducts; and carbamates. Known pesticides within these categories arelisted in The Pesticide Manual, 11th Ed., C. D. S. Tomlin, Ed., BritishCrop Protection Council, Farnham, Surry, UK (1997).

Pyrethroids that are useful in the present composition includepyrethrins and synthetic pyrethroids. The pyrethrins that are preferredfor use in the present method include, without limitation,2-allyl-4-hydroxy-3-methyl-2-cyclopenten-1-one ester of2,2-dimethyl-3-(2-methylpropenyl)-cyclopropane carboxylic acid, and/or(2-methyl-1-propenyl)-2-methoxy-4-oxo-3-(2-propenyl)-2-cyclopenten-1-ylester and mixtures of cis and trans isomers thereof (Chemical AbstractsService Registry Number (“CAS RN”) 8003-34-7).

Synthetic pyrethroids that are preferred for use in the presentinvention include (s)-cyano(3-phenoxyphenyl)methyl-4-chloro alpha(1-methylethyl)benzeneacetate (fenvalerate, CAS RN 51630-58-1),(S)-cyano-(3-phenoxyphenyl)methyl(S)-4-chloro-alpha-(1-methylethyl)benzeneacetate (esfenvalerate, CAS RN66230-04-4),(3-phenoxyphenyl)-methyl(+)cis-trans-3-(2,2-dichoroethenyl)-2,2-dimethylcyclopropanecarboxylate(permethrin, CAS RN 52645-53-1), (±)alpha-cyano-(3-phenoxyphenyl)methyl(+)-cis,trans-3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylate (cypermethrin, CAS RN 52315-07-8), (beta-cypermethrin, CASRN 65731-84-2), (theta cypermethrin, CAS RN 71697-59-1), S-cyano(3-phenoxyphenyl)methyl (±) cis/trans 3-(2,2-dichloroethenyl) 2,2dimethylcyclopropane carboxylate (zeta-cypermethrin, CAS RN 52315-07-8),(s)-alpha-cyano-3-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate (deltamethrin, CAS RN52918-63-5), alpha-cyano-3-phenoxybenzyl 2,2,3,3,-tetramethylcyclopropoanecarboxylate (fenpropathrin, CAS RN 64257-84-7),(RS)-alpha-cyano-3-phenoxybenzyl(R)-2-[2-chloro-4-(trifluoromethyl)anilino]-3-methylbutanoate(tau-fluvalinate, CAS RN 102851-06-9),(2,3,5,6-tetrafluoro-4-methylphenyl)methyl-(1-alpha,3-alpha)-(Z)-(±)-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate(tefluthrin, CAS RN 79538-32-2), (±)-cyano (3-phenoxyphenyl)methyl(±)-4-(difluoromethoxy)-alpha-(1-methyl ethyl)benzeneacetate(flucythrinate, CAS RN 70124-77-5),cyano(4-fluoro-3-phenoxyphenyl)methyl3-[2-chloro-2-(4-chlorophenyl)ethenyl]-2,2-dimethylcyclopropanecarboxylate(flumethrin, CAS RN 69770-45-2), cyano(4-fluoro-3-phenoxyphenyl) methyl3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanedarboxylate(cyfluthrin, CAS RN 68359-37-5), (beta cyfluthrin, CAS RN 68359-37-5),(transfluthrin, CAS RN 118712-89-3),(S)-alpha-cyano-3-phenoxybenzyl(Z)-(1R-cis)-2,2-dimethyl-3-[2-(2,2,2-trifluoro-trifluoromethyl-ethoxycarbonyl)vinyl]cyclopropanecarboxylate (acrinathrin, CAS RN 101007-06-1), (1R cis) S and (1S cis) Renantiomer isomer pair ofalpha-cyano-3-phenoxybenzyl-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (alpha-cypermethrin, CAS RN 67375-30-8),[1R,3S)3(1′RS)(1′,2′,2′,2′,2′-tetrabromoethyl)]-2,2-dimethylcyclopropanecarboxylicacid (s)-alpha-cyano-3-phenoxybenzyl ester (tralomethrin, CAS RN66841-25-6), cyano-(3-phenoxyphenyl)methyl2,2-dichloro-1-(4-ethoxyphenyl)cyclopropane carboxylate (cycloprothrin,CAS RN 63935-38-6), [1α, 3α(Z)]-(±)-cyano-(3-phenoxyphenyl)methyl3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate(cyhalothrin, CAS RN 68085-85-8), [1-alpha (s),3-alpha(z)]-cyano(3-phenoxyphenyl)methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate(lambda cyhalothrin, CAS RN 91465-08-6),(2-methyl-[1,1′-biphenyl]-3-yl)methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl-cyclopropanecarboxylate(bifenthrin, CAS RN 82657-04-3), 5-1-benzyl-3-furylmethyl-d-cis(1R,3S,E)2,2-dimethyl-3-(2 -oxo,-2,2,4,5 tetrahydrothiophenylidenemethyl)cyclopropanecarboxylate (kadethrin, RU15525, CASRN 58769-20-3),[5-(phenylmethyl)-3-furanyl]-3-furanyl-2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylate (resmethrin, CAS RN 10453-86-8),(1R-trans)-[5-(phenylmethyl)-3-furanyl]methyl2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylate(bioresmethrin, CAS RN 28434-01-7),3,4,5,6-tetrahydro-phthalimidomethyl-(1RS)-cis-trans-chrysanthemate(tetramethrin, CAS RN 7696-12-0), 3-phenoxybenzyl-d,I-cis,trans2,2-dimethyl-3-(2-methylpropenyl)cyclopropane carboxylate (phenothrin,CAS RN 26002-80-2); (empenthrin, CAS RN 54406-48-3); (cyphenothrin; CASRN 39515-40-7), (prallethrin, CAS RN 23031-36-9), (imiprothrin, CAS RN72963-72-5), (RS)-3-allyl-2-methyl-4-oxcyclopent-2-enyl-(1S,3R;1R,3S)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate(allethrin, CAS RN 584-79-2), (bioallethrin, CAS RN 584-79-2), and(ZXI8901, CAS RN 160791-64-0). It is believed that mixtures of one ormore of the aforementioned synthetic pyrethroids can also be used in thepresent invention. Particularly preferred synthetic pyrethroids aretefluthrin, lambda cyhalothrin, bifenthrin, permethrin and cyfluthrin.Even more preferred synthetic pyrethroids are tefluthrin and lambdacyhalothrin, and yet more preferred is tefluthrin.

Insecticides that are oxadiazine derivatives are useful in the subjectmethod. The oxadizine derivatives that are preferred for use in thepresent invention are those that are identified in U.S. Pat. No.5,852,012. More preferred oxadiazine derivatives are5-(2-chloropyrid-5-ylmethyl)-3-methyl-4-nitroiminoperhydro-1,3,5-oxadiazine,5-(2-chlorothiazol-5-ylmethyl)-3-methyl-4-nitroiminoperhydro-1,3,5-oxadiazine,3-methyl-4-nitroimino-5-(1-oxido-3-pyridinomethyl)perhydro-1,3,5-oxadiazine,5-(2-chloro-1-oxido-5-pyridiniomethyl)-3-methyl-4-nitroiminoperhydro-1,3,5-oxidiazine;and3-methyl-5-(2-methylpyrid-5-ylmethyl)-4-nitroiminoperhydro-1,3,5-oxadiazine.Even more preferred is thiamethoxam (CAS RN 153719-23-4).

Chloronicotinyl insecticides are also useful in the subject method.Chloronicotinyls that are preferred for use in the subject compositionare described in U.S. Pat. No. 5,952,358, and include acetamiprid((E)-N-[(6-chloro-3-pyridinyl)methyl]-N′-cyano-N-methyleneimidamide, CASRN 135410-20-7), imidacloprid(1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimime, CAS RN138261-41-3), and nitenpyram(N-[(6-chloro-3-pyridinyl)methyl]-N-ethyl-N′-methyl-2-nitro-1,1-ethenediamine,CAS RN 120738-89-8).

Nitroguanidine insecticides are useful in the present method. Suchnitroguanidines include those described in U.S. Pat. Nos. 5,633,375,5,034,404 and 5,245,040, and, in particular, TI-435(N-[(2-chloro-5-thiazoyl)methyl]-N′-methyl-N″-nitro,[C(E)]-(9CI)-guanidine, (having a common name of clothianidin) CAS RN210880-92-5).

Pyrrols, pyrazoles and phenyl pyrazoles that are useful in the presentmethod include those that are described in U.S. Pat. No. 5,952,358.Preferred pyrazoles include chlorfenapyr(4-bromo-2-(4-chlorophenyl)-1-ethoxymethyl-5-trifluoromethylpyrrole-3-carbonitrile,CAS RN 122453-73-0), fenpyroximate((E)-1,1-dimethylethyl-4[[[[(1,3-dimethyl-5-phenoxy-1H-pyrazole-4-yl)methylene]amino]oxy]methyl]benzoate,CAS RN 111812-58-9), and tebufenpyrad(4-chloro-N[[4-1,1-dimethylethyl)phenyl]methyl]-3-ethyl-1-methyl-1H-pyrazole-5-carboxamide,CAS RN 119168-77-3). A preferred phenyl pyrazole is fipronil(5-amino-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(1R,S)-(trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile,CAS RN 120068-37-3).

Diacylhydrazines that are useful in the present invention includehalofenozide(4-chlorobenzoate-2-benzoyl-2-(1,1-dimethylethyl)-hydrazide, CAS RN112226-61-6), methoxyfenozide (RH-2485;N-tert-butyl-N′-(3-methoxy-o-toluoyl)-3,5-xylohydrazide, CAS RN161050-58-4), and tebufenozide (3,5-dimethylbenzoic acid1-(1,1-dimethylethyl)-2-(4-ethylbenzoyl)hydrazide, CAS RN 112410-23-8).

Triazoles, such as amitrole (CAS RN 61-82-5) and triazamate are usefulin the method of the present invention. A preferred triazole istriazamate(ethyl-[[1-[(dimethylamino)carbonyl]-3-(1,1-dimethylethyl)-1H-1,2,4-triazol-5-yl]thio]acetate,CAS RN 112143-82-5).

Biological/fermentation products, such as avermectin (abamectin, CAS RN71751-41-2) and spinosad (XDE-105, CAS RN 131929-60-7) are useful in thepresent method.

Organophosphate insecticides are also useful as one of the components ofthe present method. Preferred organophophate insecticides includeacephate (CAS RN 30560-19-1), chlorpyrifos (CAS RN 2921-88-2),chlorpyrifos-methyl (CAS RN 5598-13-0), diazinon (CAS RN 333-41-5),fenamiphos (CAS RN 22224-92-6), and malathion (CAS RN 121-75-5).

In addition, carbamate insecticides are useful in the subject method.Preferred carbamate insecticides are aldicarb (CAS RN 116-06-3),carbaryl (CAS RN 63-25-2), carbofuran (CAS RN 1563-66-2), oxamyl (CAS RN23135-22-0) and thiodicarb (CAS RN 59669-26-0).

Fungicides that are useful in the present invention includetebuconazole, simeconazole, fludioxonil, fluquinconazole,difenoconazole,4,5-dimethyl-N-(2-propenyl)-2-(trimethylsilyl)-3-thiophenecarboxamide(silthiopham), hexaconazole, etaconazole, propiconazole, triticonazole,flutriafol, epoxiconazole, fenbuconazole, bromuconazole, penconazole,imazalil, tetraconazole, flusilazole, metconazole, diniconazole,myclobutanil, triadimenol, bitertanol, pyremethanil, cyprodinil,tridemorph, fenpropimorph, kresoxim-methyl, azoxystrobin, ZEN90160,fenpiclonil, benalaxyl, furalaxyl, metalaxyl, R-metalaxyl, orfurace,oxadixyl, carboxin, prochloraz, trifulmizole, pyrifenox,acibenzolar-5-methyl, chlorothalonil, cymoaxnil, dimethomorph,famoxadone, quinoxyfen, fenpropidine, spiroxamine, triazoxide,BAS50001F, hymexazole, pencycuron, fenamidone, guazatine, andcyproconazole.

When a pesticide is described herein, it is to be understood that thedescription is intended to include salt forms of the pesticide as wellas any isomeric and/or tautomeric form of the pesticide that exhibitsthe same activity as the form of the pesticide that is described.

The pesticides that are useful in the present method can be of any gradeor purity that pass in the trade as such pesticide. Other materials thataccompany the pesticides in commercial preparations as impurities can betolerated in the subject methods and compositions, as long as such othermaterials do not destabilize the composition or significantly reduce ordestroy the activity of any of the pesticide components against a targetpest(s). One of ordinary skill in the art of the production ofpesticides can readily identify those impurities that can be toleratedand those that cannot.

The agricultural actives that are useful in the present invention can beprovided in solid or liquid form, and can be provided as emulsions,dispersions, solutions, or in particulate form. The actives can be aloneor can be in combination with other materials, as long as such othermaterials do not destabilize, or significantly reduce or destroy theactivity of the active.

The present method can be applied to seeds that have already beentreated by others, such as commercially available treated seeds, but thenovel method can also include the step of treating seeds with an active.When treatment of a seed with an active is included in the presentmethod, it is preferred that the treatment is carried out so that anevenly distributed coating of the pesticide is applied to the outersurface of the seed without loss of pesticide due to excess liquidfalling off of the seed during or after the treatment. After addition ofthe active, the seeds must not be dried and agitated so long that theactive is abraded off the seed due to dusting and scuffing.

The amount of active that is applied to the seed can be any amount, butis preferably between about 0.5 gm of active ingredient/100 kg of seedand about 1,000 gm/100 kg of seed; more preferably between about 25 gmand about 600 gm/100 kg of seed, and even more preferably between about50 gm and about 400 gm/100 kg of seed.

The active can be applied to the seed in any form and such forms ascapsule suspensions (CS), emulsifiable concentrates (EC), emulsions inoil or water (EO and EW), granules (GR), suspension concentrates (SC),soluble granules (SG), soluble concentrates (SL), soluble powders (SP),and water dispersible granules (WG) are suitable. It is preferred toapply the active to the seed in the form of a flowable liquid. Theactive can be in a true solution in the liquid, or it can be present assmall droplets or particles to form a suspension, dispersion oremulsion. Since many pesticides have low water solubility, it ispreferred that when water is the liquid, an aqueous dispersion,suspension, or emulsion of the pesticide be used, and that the pesticidebe present in the dispersion, suspension, or emulsion in the form ofsmall particles or droplets. As used herein, the term “suspension” willbe considered to include any form of liquid containing small particles,and to include the terms dispersion and emulsion.

The particles of pesticide in the liquid suspension can be of any sizethat permits the suspension to be applied to the seed by any means, suchas, for example, by spraying. It is preferred that the particles ofpesticide in the suspension have a number average nominal size of lessthan about 10 microns, more preferably of less than about 5 microns,even more preferably of less than about 2 microns, and even morepreferably of less than about 1 micron (be “sub-micron” in size). It isbelieved that the use of such small particles causes the pesticide toform a more stable and homogenous suspension—thereby allowing a moreeven distribution of the pesticide over the surface of the seed, andthat the small particles are less subject to abrasion from the treatedseed after the pesticide treatment has been applied.

The active can be applied to the seed in any type of conventional seedtreatment or coating equipment. Application in a seed treating machinehaving the characteristics of a CMS seed coating machine (VectorCorporation, Marion, Iowa), for example, has been found to be suitable.One method that has been found to be successful for applying apesticide, such as imidacloprid, to seed, is to mill the imidacloprid to1-2 micron, or to sub-micron, size and then to add the small particlesof imidacloprid to water to form an aqueous suspension. A mill that iscapable of reducing solids to fine particles, such as a Mirco-JetPulverizer air mill, available from Fluid Energy Processing andEquipment Company, Hatfield, Pa., can be used for the size reduction.

The concentration of the pesticide in the suspension should be lowenough to permit easy handling and application of the suspension to theseed—such as by spraying—and thorough distribution of the pesticideamong the seeds so that the outer surface of each seed is substantiallycovered. However, the concentration should be high enough that, whenused in combination with the other parameters of seed treatment, toavoid the loss of pesticide from the seeds by dripping or pooling of thetreating liquid suspension. Pesticide concentrations of between about0.1% and about 50%, by weight, are useful for such suspensions,preferred are concentrations between about 0.5% and 15%, by weight, evenmore preferred are concentrations between about 0.6% and about 5%, andyet more preferred are concentrations of the pesticide between about 1%and 3%, by weight of the suspension. Sticking agents and dyes can alsobe added to the pesticide suspension to promote the adherence of thesuspension to the seeds and to identify the seeds as having beentreated.

A desired amount of the suspension of the pesticide is sprayed onto theseed in, for example, a CMS seed treater, over a period of time that islong enough to permit thorough distribution of the suspension over theseed, but short enough so that the treated seed do not completely dry.It is believed that if the treated seed are allowed to remain in aheated seed treater until the suspension is completely dry, the dangerof loss of the pesticide by abrasion increases. When the exittemperature of the heated air circulating through the CMS machine isheld to about 95° F., and the aqueous suspension contains about 1.6% byweight imidacloprid and 8% by weight of a sticking agent, an applicationtime of between about 3 minutes and about 20 minutes is suitable, and anapplication time of between about 5 and about 15 minutes is preferred.

After an agricultural active has been applied to the seed, the novelcoating can be applied. It is preferred that the polymer of the subjectcoating be applied to the seed in the form of a film of a liquidsuspension, dispersion or emulsion. As used herein, when describing thecoating the term “emulsion” will be understood to include allsuspensions, dispersions and emulsions. When the liquid in which theactive is distributed is water, the emulsion can be termed a latex. Itwill be understood that when the term “film” is used in thisspecification, it generally applies to the film of the polymer emulsionin liquid form after application to the seed, unless the contextsuggests otherwise. Likewise, the term “coating” applies to the coatingon the seed that is formed from the curing of the film. When a filmcontaining the active is applied to the seed, it is preferred that thefilm substantially covers the surface of the seed. However, whilepreferable, such substantial coverage is not required in order to obtainthe advantages of the invention.

The liquid in which the active is suspended is one in which both theactive and the polymer have low solubility. When it is said that theactive has low solubility in the liquid, it is meant that the solubilityof the active in the liquid at 20° C. is less than about 10 g/l. It ispreferred that the solubility of the active in the liquid at 20° C. isless than about 1,000 mg/l, a solubility of less than about 200 mg/l ismore preferred, less than about 100 mg/l is even more preferred, andless than about 50 mg/l is even more preferred.

When it is said that the polymer has low solubility in the liquid, it ismeant that the solubility of the polymer in the liquid at 25° C. is lessthan about 5%, by weight. It is preferred that the solubility of thepolymer is less than about 2%, by weight, less than about 1%, by weightis more preferred, and less than about 0.1%, by weight, is even morepreferred.

It is believed that the use of a liquid in which both the polymer andthe agricultural active have low solubility provides an advantage to thenovel method. By way of example, when the liquid is water, the polymerforms a latex when distributed in the water. A film of the latex isapplied to the treated seed, and the latex film has both hydrophobic andhydrophilic character. Without wishing to be bound to this or any othertheory, it is believed that this characteristic advantageously modulatesthe distribution of the active ingredient throughout the coating duringdrying and formation of the polymer coating. Because the activeingredient has low solubility in the liquid of the film, it is believedthat the latex permits the transfer of only a small fraction of theactive ingredient into the polymer portion of the latex coating while itis still in the emulsion, but prevents the loss of the active into theliquid. This is believed to prevent the loss of active from the surfaceof the seed and to retain the major portion of the active on the seed'ssurface and away from the interface of the coating with the surroundingenvironment. It is believed that these properties provide the desirableretardation of release rate of the active from the coated, treated seedafter the coating has formed, while providing a coating with a low levelof active on the outside surface.

Although a water-based emulsion is preferred, emulsions or dispersionsof the polymers of the present method in non-aqueous solvents, or inaqueous/non-aqueous solvent mixtures are also within the scope of theinvention.

The polymer is added to the liquid under conditions that an emulsion isformed. This can be done by the addition of finely milled particles ofthe active to the liquid, or a liquid/active mixture can be subjected tohigh shear to form the emulsion. Such emulsion-forming techniques arewell-known in the art.

The polymer can be added to the liquid in any amount, but theconcentration of the polymer in the emulsion that is used to form thefilm should be low enough to permit easy handling and application of theemulsion to the seed—such as by spraying—and thorough distribution ofthe film among the seeds so that the outer surface of each seed issubstantially covered. However, the concentration should be high enough,when used in combination with the other parameters of seed treatment, toavoid the loss of polymer from the seeds by dripping or pooling of theemulsion. It is preferred that the concentration of polymer in theemulsion at the time that a film of the emulsion is applied to the seedsis about 0.5% to about 50%, by weight, more preferred is a concentrationof about 0.5% to about 20%, by weight, even more preferred is aconcentration of about 2% to about 20%, yet more preferred is aconcentration of about 4% to about 15%, by weight, and even morepreferred is a concentration of about 5% to about 11%, by weight.

If it is desirable, materials other than the polymer can be added to theliquid in order to serve as plasticizers, emulsifiers, stabilizers,anti-oxidants, fillers, dyes, safeners, and the like. Such materials arewell known in the art.

The polymer emulsion can be applied to the seeds in the same type ofseed treatment equipment as used for the application of the activeingredient to the seeds. In fact, it is preferred that the emulsion beadded to the seeds immediately after the addition of the activeingredient and without removing the seeds from the treater. It ispreferred that a short amount of time—on the order of 30 sec. to 3minutes—elapse between the end of the application of the active and thebeginning of the application of the emulsion film. This permits somedegree of liquid removal from the treated seeds, but is not long enoughto allow the treated seeds to become completely dry.

The amount of the polymer emulsion that is added to the seeds is anamount that is sufficient to provide a coating of the desired thickness.The ratio of the weight of the film of the emulsion that is present oneach seed after the emulsion has been added relative to the weight ofthe treated seed is preferably within a range of from about 1:10 toabout 1:50, more preferred is a ratio of about 1:15 to about 1:25, evenmore preferred is a ratio within a range of about 1:16 to about 1:22,and yet more preferred that the ratio be within a range of about 1:18 toabout 1:21.

Without being bound by this or any other theory, it is believed that thecombination of the amount of the polymer film that is added to the seed,the concentration of the polymer in the emulsion, and the time requiredfor the addition of the emulsion to the seed is important to provide anovercoat that retains substantially all of the active ingredient on theseed and provides an exterior surface that has a very low concentrationof the active ingredient.

After the film of the polymer emulsion has been applied to the seed, itis cured to form the polymer coating. When it is said that the film is“cured”, or when “curing the film” is referred to, what is meant is thata solid coating of the polymer is formed from the polymer in the film.Curing is often the result of drying of the liquid from the film, butcan also be carried out by chemical reaction, adsorption, sequestration,or other forms of polymer curing that are known in the art.

The subject coating is insoluble in water, as described above, and ispresent on at least some part of the outer surface of each seed. It ispreferred that the coating completely cover the outer surface of eachseed. Although the ratio of the weight of the coating relative to theweight of the treated seed can vary over a wide range, it is preferredthat the ratio be within a range of from about 1:1 to about 1:1,000,more preferably within a range of about 1:10 to about 1:600, and evenmore preferably within a range of about 1:20 to about 1:400.

It is believed that the present coating contains some of the activeingredient distributed throughout its thickness. However, because thepreferred method of applying the coating is to apply a film of acontrolled amount of the particular emulsion to the surface of each seed(rather than to immerse the seed in a large amount of polymer) it isbelieved that only a small portion of the active on the seed diffusesfrom the surface of the seed into the coating during the time the filmdries and forms a solid coating. It is believed that the concentrationof the active in the coating is highest at or near the surface of theseed and decreases to a low level at the interface of the coating withthe surrounding environment (the outer surface of the coating).

Although the coating is substantially water insoluble, it must nottotally prevent the seed from imbibing water in order to germinate.Therefore, the coating must be sufficiently permeable to water so thatthe seed can imbibe moisture for germination, but still must retard therelease of the active. Moreover, the coating must be sufficientlypermeable to oxygen and carbon dioxide so that the normal respiration ofthe seed is not significantly impaired.

Seeds that have been treated by the subject method can be stored,handled and planted like any other seeds. Similar methods and conditionscan be used as are used with any other treated, or non-treated seeds andthe same handling and planting equipment can be used that is used forconventional seeds.

Athough the subject coating reduces the exposure of persons handling thetreated and coated seed to the active, suitable precautions to protectsuch personnel should be taken.

The following examples describe preferred embodiments within the scopeof the invention. Other embodiments within the scope of the claimsherein will be apparent to one skilled in the art from consideration ofthe specification or practice of the invention as disclosed herein. Itis intended that the specification, together with the examples, beconsidered exemplary only, with the scope and spirit of the inventionbeing indicated by the claims which follow the examples. In the examplesall percentages are given on a weight basis unless otherwise indicated.

EXAMPLE 1

This illustrates the treatment of corn seed with imidacloprid.

A coating suspension was prepared by mixing water (133.6 g) at roomtemperature, with Vinamul 18132 (8.4 g, available from Vinamul LimitedInc.), Seedkare Luster Kote Plus Red (7.03 g, available from Sub-SaharaCo.), and imidacloprid (2.47 g, available from the Gustafson Company).Prior to preparing the suspension, the size of the imidaclopridparticles was reduced from over 100 microns to a nominal average size ofapproximately 1-2 microns. The size reduction can be carried out bymilling for a time sufficient to produce imidacloprid particles having anominal size of below about 1-2 microns.

The ingredients were then mixed together and the mixture was stirredwith a mechanical stirrer at medium speed at room temperature for 20minutes. At this time the coating suspension was ready for applicationto the seed.

Corn seed (908.21 g, Asgrow RX601, Lot LF OZ34982, available from AsgrowSeed Company, L.L.C.) was preheated with agitation in the drum of a CMSseed treatment machine (model PSC-0.5; available from VectorCorporation, Marion, Iowa) for three minutes at one-half rotation of thedrum every minute. The inlet and exhaust temperatures of the air flowinginto and out of the CMS machine were set to be controlled at 101° F. and90° F. respectively. The actual exhaust temperature was 99° F. The drumspeed was set at 20 rpm and the drum position angle was down. Atomizingair flow rate for spray application of the coating suspension was 50 cfhand the tube size on the pump was 16. The pump speed was set at 5.5.Over a period of 14.5 minutes, the coating suspension was sprayeddirectly on the seed through a nozzle. A pulse spray mode was used. Theweight of the seed after application of the coating suspension was921.94 g.

EXAMPLE 2

This illustrates the treatment of corn seed with imidacloprid andsubsequent coating with a polymer latex having a glass transitiontemperature of 15° C.

Corn seed (908.13 g) was treated with a coating suspension thatcontained water (133.6 g), imidacloprid (2.48 g; milled as described inExample 1), Vinamul 18132 (8.39 g), and Seedkare Lusterkote Plus Red(7.03 g). The coating suspension was prepared and applied to corn seedas described in Comparative Example 1, except that the time to apply thesuspension was about 8 minutes.

After the coating suspension had been applied to the corn seed, andwhile the treated seed was still in the drum of the CMS machine, anaqueous emulsion of a polymer latex was applied to the seed. The polymerlatex emulsion was prepared by mixing water (38.1 g) at roomtemperature, with polymer latex (11.7 g, NMS-7 polymer latex having asolids content of 45.8% by weight; and having a glass transitiontemperature (T_(g)) of 15° C., available from the Stepan Company,Northfield, Ill.). The conditions for the CMS Treater during theovercoating process were as follows: the inlet temperature was set for106° F.; exhaust temperature (set) 90° F.; exhaust temperature (actual)99° F.; seed temperature during overcoating was 34.2° F.; drum speed 20rpm, drum angle was down, atomizing air pressure was 50 psi; tube sizeon the pump was 16; pump speed was 5; and time to apply the overcoatingemulsion was 2 min. 45 sec. The weight of the seed after treating andovercoating was 929.49 g.

EXAMPLE 3

This illustrates the treatment of corn seed with imidacloprid andsubsequent coating with a polymer latex having a glass transitiontemperature of 25° C.

Corn seed (908.24 g) was treated with a coating suspension thatcontained water (133.6 g), imidacloprid (2.47 g), Vinamul 18132 (8.39g), and Seedkare Lusterkote Plus Red (7.02 g). The coating suspensionwas prepared and applied to corn seed as described in Example 2.

After the coating suspension had been applied to the corn seed, anaqueous emulsion of a polymer latex was applied to the seed as describedin Example 2. The polymer latex emulsion was prepared by mixing water(33.1 g) at room temperature, with polymer latex (12.7 g, NMS-7 polymerlatex having a solids content of 39.6% by weight; and having a glasstransition temperature (T_(g)) of 25° C., available from the StepanCompany, Northfield, Ill.). The conditions for the CMS Treater duringthe overcoating process were the same as in Example 2, and the time toapply the overcoating emulsion was 3 min. 10 sec. The weight of the seedafter treating and overcoating was 929.31 g.

EXAMPLE 4

This illustrates the treatment of corn seed with imidacloprid andsubsequent coating with an aqueous dispersion of ethylcellulose.

Corn seed (908.14 g) was treated with a coating suspension thatcontained water (133.6 g), imidacloprid (2.47 g), Vinamul 18132 (8.38g), and Seedkare Lusterkote Plus Red (7.02 g). The coating suspensionwas prepared and applied to corn seed as described in Example 2.

After the coating suspension had been applied to the corn seed, anaqueous dispersion of ethylcellulose was applied to the seed asdescribed in Example 2. The ethylcellulose dispersion was prepared bymixing water (30 g) at room temperature, with ethylcellulose (20.16 g,Surelease polymer, Lot E-7-19010; an off-white, turbid, liquiddispersion having a solids content of 24%-26% of ethylcellulose 20 cP,and also containing ammonium hydroxide, medium chain triglycerides andoleic acid in small amounts; available from Colorcon Company). Theconditions for the CMS Treater during the overcoating process were thesame as in Example 2, and the time to apply the overcoating emulsion was3 min. 30 sec. The weight of the seed after treating and overcoating was929.07 g.

EXAMPLE 5

This illustrates the treatment of corn seed with imidacloprid andsubsequent coating Aquacoat Type ECD formulation of ethylcellulose.

Corn seed (908.48 g) was treated with a coating suspension thatcontained water (133.6 g), imidacloprid (2.47 g), Vinamul 18132 (8.38g), and Seedkare Lusterkote Plus Red (7.05 g). The coating suspensionwas prepared and applied to corn seed as described in Example 2.

After the coating suspension had been applied to the corn seed, AquacoatType ECD-30 aqueous dispersion of ethylcellulose (ECD) was applied tothe seed as described in Example 2. The ECD dispersion was prepared bymixing water (33.2 g) at room temperature, with Aquacoat Type ECD-30(16.8 g of a while liquid dispersion having 27% by weight ofethylcellulose; the dispersion having a total solids content of 30%, andcontaining cetyl alcohol and sodium lauryl sulfate. Available from FMCCorporation). The conditions for the CMS Treater during the overcoatingprocess were the same as in Example 2, and the time to apply theovercoating emulsion was 3 min. 40 sec. The weight of the seed aftertreating and overcoating was 927.7 g.

EXAMPLE 6

This illustrates the treatment of corn seed with imidacloprid andsubsequent coating with a vinyl acetate-ethylene copolymer.

Corn seed (908.14 g) was treated with a coating suspension thatcontained water (133.6 g), imidacloprid (2.47 g), Vinamul 18132 (8.37g), and Seedkare Lusterkote Plus Red (7.03 g). The coating suspensionwas prepared and applied to corn seed as described in Example 2.

After the coating suspension had been applied to the corn seed, anaqueous dispersion of Airflex 500 was applied to the seed as describedin Example 2. The Airflex 500 dispersion was prepared by mixing water(45.38 g) at room temperature, with Airflex 500 (4.62 g; Airflex 500 isa fine-particle-size aqueous dispersion of a vinyl acetate-ethylenecopolymer; the emulsion is used as a base for interior and exteriorpaints and other flexible coatings. The solids content of the emulsionis 55% by weight and the average particle size is 0.17 microns.Available from Air Products Company). The conditions for the CMS Treaterduring the overcoating process were the same as in Example 2, and thetime to apply the overcoating emulsion was 5 min. 10 sec. The weight ofthe seed after treating and overcoating was 924.23 g.

EXAMPLE 7

This illustrates the release profiles of imidacloprid into water fromtreated corn seeds with and without polymer overcoating and shows therelease-retarding effect of certain polymer overcoats.

The treated corn seed from Examples 1 through 5 was tested for therelease rate of imidacloprid into excess water. Treated seeds wereplaced in an amount of water sufficient that at 100% release of theactive from the treated seeds, the total active present in the water isless than approximately one-third the water solubility level of theactive. The water containing the seeds is then agitated by shaking. Atintervals, an aliquot is taken and filtered to separate the active thatis dissolved in the water from the active that remains on the seed, orremains in the form of a controlled release matrix. The filtered aliquotis then assayed for active present. Release curves show the percent ofthe total active that was originally present on the seeds that has beenreleased into the water as a function of the time of immersion.

In a typical sample, treated seeds containing approximately 45 mg ofimidacloprid were placed in a 16 ounce bottle along with 450 ml ofwater. The total amount of imidacloprid in the bottle was calculated tobe about 100 ppm, which is less than one-third of the water solubilitylimit of imidacloprid at room temperature (about 510 ppm). The bottlecontaining the water and the seeds was then inverted approximately 100times and an aliquot of liquid was removed and the time of removal wasnoted. The bottle was then placed on a platform shaker and agitateduntil time for the next sample withdrawal. The aliquot was filtered witha 0.45 micron PTFE filter and the filtered aliquot was assayed forimidacloprid content by HPLC. An Alltech Alltime C18 reverse phasecolumn (5 micron particle size with column dimensions of 250×4.5 mm) wasused with a flow rate of 1.2 ml/min and an injection volume of 20microliters. The mobile phase contained 30% of acetonitrile and 70% ofwater. The UV detector (Varian 9050) was set at 220 nm and the retentiontime for imidacloprid was between 6 and 7 min. For subsequent timepoints of the release curve, the procedure described above was used todetermine the concentration of active in the water.

When seeds were treated with, for example, tebuconazole, the sameprocedure was used to determine the release rate, except that therelative amounts of treated seeds and water were adjusted to maintainthe maximum level of the active at less than one-third of its solubilitylevel.

The results of the release rate test are shown in FIG. 1, where thepercent release of the total imidacloprid on the seed is shown as afunction of time for each of the treated and coated seeds and for thetreated and uncoated seed. It can be seen that imidacloprid was lostfrom the uncoated seed more rapidly that for any of the seeds having apolymer coating. However, the release rate varied significantlyaccording to the type of polymer and the glass transition temperature ofthe polymer. Seeds treated with the two Stepan NMS-7 latex polymersprovided the highest reduction in release rate, and showed that therelease rate could be varied by varying the glass transition temperatureof the polymer coating. In this instance, it was seen that the polymerhaving the lower T_(g) provided the lower release rate. However, it isbelieved that the effect of T_(g) upon release rate may be reversed forpolymers having different structures. It is believed that this showsthat with a given polymer, the release rate of the active can becontrolled by selecting a polymer having a T_(g) that will provide thedesired rate.

EXAMPLE 8

This illustrates the treatment of cotton seed with imidacloprid andshows the effect on imidacloprid release rate of overcoating the treatedcotton seed with a polymer coating derived from an aqueous latex.

Cotton seed (908 g, which had been received from Deltapine Company(Boligard cotton seed with Roundup Ready® technology; Lot# 458BR-S-9299-2, treatment code 2) was treated with a coating suspensionthat contained water (133.6 g), Vinamul 18132 (8.46 g), SeedkareLusterkote Plus Red (7.04 g) and imidacloprid (2.47 g). The coatingsuspension was prepared and applied to the seed in the manner describedin Example 2, except that cotton seed was substituted for corn seed.

After the seed was treated with the imidacloprid suspension, a portionof the treated seed were removed from the CMS machine and the remainderof the seed were left in the machine. An aqueous emulsion of a polymerlatex (12.7 g of NMS-7, polymer latex, having a T_(g) of 25° C.,available from Stepan Company, diluted with 38.1 g of water) was appliedto the seed as described in Example 2.

Samples of the treated cotton seed with and without the polymerovercoating were tested by the same technique as described in Example 7to determine the release profiles of imidacloprid into excess water.

The release profiles of imidacloprid from treated cotton seed with andwithout the novel coating are shown in FIG. 2. It can be seen that theuncoated seeds lost over 90%, by weight, of the imidacloprid that hadbeen deposited on the treated seeds within 5 hours. However, cottonseeds having the coating lost only 30% or less in the same time. Thisshowed that the novel coating could be applied to treated cotton seed aswell as to corn seed, and that the coating provided the sameadvantageous retardation of release rate of the imidacloprid as shownfor coatings applied to corn.

EXAMPLE 9

This illustrates the effect of overcoating corn seed treated withtebuconazole with polymers having different glass transitiontemperatures.

Three separate batches of corn seed (908 g) were treated in a CMS seedtreater with tebuconazole (supplied as RAXIL® in a liquid mixturecontaining 6% by weight tebuconazole, RAXIL® is available from BayerCorporation). A suspension of RAXIL® (15.2 ml) was prepared by mixing itwith Vinamul 18132 (8.32 g) and Seedkare Lusterkote Plus Red (7.0 g) inwater (133.6 g). The suspension was applied to corn seed by the methodsdescribed in Example 2.

One batch of the corn seed treated with tebuconazole was left withoutfurther treatment.

For the other two batches of treated corn seed, after the tebuconazolecoating suspension had been applied to the seed, a polymer latexemulsion was applied by the methods described in Example 2. One batchwas coated with a latex emulsion prepared by mixing water (38.1 g) atroom temperature with polymer latex (11.1 g of Stepan NMS-7 polymerlatex having a solids content of 45.8% by weight, and having a T_(g)=15°C., available from Stepan Co., Northfield, Ill.). The emulsion wasapplied to the seeds within a period of 4 min. 20 sec. The weight of thetreated and overcoated seeds was 933.1 g.

The final batch of tebuconazole treated corn seed was overcoated asdescribed above, except with a latex emulsion prepared by mixing water(33.1 g) at room temperature with polymer latex (12.7 g of Stepan NMS-7polymer latex having a solids content of 39.6% by weight, and having aT_(g)=25° C., available from Stepan Co., Northfield, Ill.). The emulsionwas applied to the seeds within a period of 4 min. 50 sec. The weight ofthe treated and overcoated seeds was 931.58 g.

The release rate of tebuconazole from the three batches of treated cornseed was determined as described in Example 7, except that the assay wasfor tebuconazole rather than imidacloprid. The release rate profiles fortebuconazole into water are shown in FIG. 3 and indicate that coatingwith either polymer provides a controlled rate of release of thetebuconazole relative to the seeds having no overcoating. Littledifference in the release rate was noticed as a function of the T_(g) ofthe polymers in this test.

All references cited in this specification, including without limitationall papers, publications, presentations, texts, reports, manuscripts,brochures, internet postings, journal articles, periodicals, and thelike, are hereby incorporated by reference. The citation and/ordiscussion of the references herein is intended merely to summarize theassertions made by their authors and no admission is made that anyreference constitutes prior art. Applicants reserve the right tochallenge the accuracy and pertinency of the cited references.

In view of the above, it will be seen that the several advantages of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above methods and compositionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

1. A method of controlling the release rate of an agricultural active ingredient from a seed treated with the active ingredient, the method comprising the steps of: providing a seed that has been treated with an agricultural active ingredient; applying to the treated seed a film comprising an emulsion of a polymer in a liquid in which both the agricultural active ingredient and the polymer have low levels of solubility; and curing the film to form a water insoluble polymer coating on the surface of the treated seed.
 2. The method according to claim 1, wherein the liquid is water.
 3. The method according to claim 2, wherein the ratio of the weight of the film to the weight of the treated seed is from about 1:10 to about 1:50, and the weight percent of the polymer in the film at the time the film is applied to the seed is from about 0.5 percent to about 25 percent.
 4. The method according to claim 3, wherein the ratio of the weight of the film to the weight of the treated seed is from about 1:16 to about 1:22, and the weight percent of the polymer in the film at the time the film is applied to the seed is from about 4 percent to about 15 percent.
 5. The method according to claim 4, wherein the ratio of the weight of the film to the weight of the treated seed is from about 1:18 to about 1:21, and the weight percent of the polymer in the film at the time the film is applied to the seed is from about 5 percent to about 11 percent.
 6. The method according to claim 2, wherein the film additionally comprises a non-migrating surfactant.
 7. The method according to claim 6, wherein the water insoluble polymer and the non-migrating surfactant and the relative amounts of each are selected so that the polymer coating that is formed from the water insoluble polymer and the non-migrating surfactant has a glass transition temperature within a pre-selected range, thereby providing a coating which retards the release rate of the agricultural active ingredient from the seed by a desired amount.
 8. The method according to claim 7, wherein the glass transition temperature of the polymer coating is within the range of from about −5° C. to about 75° C.
 9. The method according to claim 8, wherein the glass transition temperature of the polymer coating is within the range of from about 10° C. to about 50° C.
 10. The method according to claim 9, wherein the glass transition temperature of the polymer coating is within the range of from about 15° C. to about 40° C.
 11. The method according to claim 10, wherein the glass transition temperature of the polymer coating is within the range of from about 15° C. to about 25° C.
 12. The method according to claim 3, wherein the agricultural active ingredient is a pesticide.
 13. The method according to claim 12, wherein the pesticide is selected from the group consisting of herbicides, insecticides, acaracides, fungicides, nematocides, and bactericides.
 14. The method according to claim 13, wherein the agricultural active ingredient is an insecticide.
 15. The method according to claim 14, wherein the agricultural active ingredient is selected from the group consisting of pyrethrins including, 2-allyl-4-hydroxy-3-methyl-2-cyclopenten-1-one ester of 2,2-dimethyl-3-(2methyl propenyl)-cyclopropane carboxylic acid, and/or (2-methyl-1-propenyl)-2-methoxy-4-oxo-3-(2 propenyl)-2-cyclopenten-1-yl ester and mixtures of cis and trans isomers thereof; synthetic pyrethroids including (s)-cyano(3-phenoxyphenyl)methyl-4-chloro-alpha-(1-methylethyl)benzeneacetate (fenvalerate), (S)-cyano (3-phenoxyphenyl)methyl (S)-4-chloro-alpha-(1-methylethyl)benzeneacetate (esfenvalerate), (3-phenoxyphenyl)-methyl(+)cis-trans-3-(2,2-dichoroethenyl)-2,2-dimethylcyclopropanecarboxylate (permethrin), (±) alpha-cyano-(3-phenoxyphenyl)methyl(+)-cis,trans-3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylate (cypermethrin), beta-cypermethrin, theta cypermethrin, S-cyano (3-phenoxyphenyl)methyl (±) cis/trans 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate (zeta-cypermethrin), (s)-alpha-cyano-3-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate (deltamethrin), alpha-cyano-3-phenoxybenzyl-2,2,3,3,-tetramethyl cyclopropoanecarboxylate (fenpropathrin), (RS)-alpha-cyano-3-phenoxybenzyl(R)-2-[2-chloro-4-(trifluoromethyl)anilino]-3-methylbutanoate (tau-fluvalinate), (2,3,5,6-tetrafluoro-4-methylphenyl)-methyl-(1-alpha, 3-alpha)-(Z)-(±)-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate (tefluthrin), (±)-cyano-(3-phenoxyphenyl) methyl (±)-4-(difluoromethoxy)-alpha-(1-methylethyl)benzeneacetate (flucythrinate), cyano(4-fluoro-3-phenoxyphenyl)methyl 3-[2-chloro-2-(4-chlorophenyl)ethenyl]-2,2-dimethylcyclopropanecarboxylate (flumethrin), cyano(4-fluoro-3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanedarboxylate (cyfluthrin), beta cyfluthrin, transfluthrin, (S)-alpha-cyano-3-phenoxybenzyl(Z)-(1R-cis)-2,2-dimethyl-3-[2-(2,2,2-trifluoro-trifluoromethyl-ethoxycarbonyl)vinyl]cyclopropane carboxylate (acrinathrin), (1R cis) S and (1S cis) R enantiomer isomer pair of alpha-cyano-3-phenoxybenzyl-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (alpha-cypermethrin), [1R,3S)3(1′RS)(1′,2′,2′,2′-tetrabromoethyl)]-2,2-dimethyl cyclopropanecarboxylic acid (s)-alpha-cyano-3-phenoxybenzyl ester (tralomethrin), cyano-(3-phenoxyphenyl)methyl-2,2-dichloro-1-(4-ethoxyphenyl)cyclopropanecarboxylate (cycloprothrin), [1α, 3α(Z)]-(±)-cyano-(3-phenoxyphenyl)methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-cimethylcyclopropanecarboxylate (cyhalothrin), [1-alpha (s), 3-alpha(z)]-cyano(3-phenoxyphenyl)methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate (lambda cyhalothrin), (2-methyl [1,1′-biphenyl]-3-yl)methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl-cyclopropanecarboxylate (bifenthrin), 5-1-benzyl-3-furylmethyl-d-cis(1R,3S, E)2,2-dimethyl-3-(2-oxo,-2,2,4,5-tetrahydrothiophenylidenemethyl)cyclopropane carboxylate (kadethrin), [5-(phenylmethyl)-3-furanyl]-3-furanyl 2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylate (resmethrin). (1R-trans)-[5-(phenylmethyl)-3-furanyl]methyl 2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylate (bioresmethrin), 3,4,5,6-tetrahydro-phthalimidomethyl-(1RS)-cis-trans-chrysanthemate (tetramethrin), 3-phenoxybenzyl-d,1-cis,trans 2,2-dimethyl-3-(2-methylpropenyl)cyclopropanecarboxylate (phenothrin), empenthrin, cyphenothrin, prallethrin, imiprothrin, (RS)-3-allyl-2-methyl-4-oxcyclopent-2-enyl-(1S,3R; 1R,3S)-2,2-dimethyl-3-(2-methylprop-1-enyl) cyclopropane carboxylate (allethrin), bioallethrin, and ZXI8901; oxadiazine derivatives including 5-(2-chloropyrid-5-ylmethyl)-3-methyl-4-nitroiminoperhydro-1,3,5-oxadiazine, 5-(2-chlorothiazol-5-ylmethyl)-3-methyl-4-nitroiminoperhydro-1,3,5-oxadiazine, 3-methyl-4-nitroimino-5-(1-oxido-3-pyridinomethyl)perhydro-1,3,5-oxadiazine, 5-(2-chloro-1-oxido-5-pyridiniomethyl)-3-methyl-4-nitroiminoperhydro-1,3,5-oxidiazine, 3-methyl-5-(2-methylpyrid-5-ylmethyl)-4-nitroiminoperhydro-1,3,5-oxadiazine, and thiamethoxam; chloronicotinyl insecticides including acetamiprid ((E)-N-[(6-chloro-3-pyridinyl)methyl]-N′-cyano-N-methyleneimidamide), imidacloprid (1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimime), and nitenpyram (N-[(6-chloro-3-pyridinyl)methyl]-N-ethyl-N′-methyl-2-nitro-1,1-ethenediamine); nitroguanidine, including TI-435; pyrroles; pyrazoles chlorfenapyr (4-bromo-2-(4-chlorophenyl)-1-ethoxymethyl-5-trifluoromethylpyrrole-3-carbonitrile), fenpyroximate ((E)-1,1-dimethylethyl-4[[[[(1,3-dimethyl-5-phenoxy-1H-pyrazole-4-yl)methylene]amino]oxy]methyl]benzoate), and tebufenpyrad (4-chloro-N[[4-1,1-dimethylethyl)phenyl]methyl]-3-ethyl-1-methyl-1H-pyrazole-5-carboxamide); phenyl pyrazoles including fipronil (5-amino-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(1R,S)-(trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile); diacylhydrazines including halofenozide (4-chlorobenzoate-2-benzoyl-2-(1,1-dimethylethyl)-hydrazide), methoxyfenozide (RH-2485, N-tert-butyl-N′-(3-methoxy-o-toluoyl)-3,5-xylohydrazide), and tebufenozide (3,5-dimethylbenzoic acid 1-(1,1-dimethylethyl)-2,(4-ethylbenzoyl)hydrazide); triazoles including amitrole and triazamate; biological/fermentation products including avermectin (abamectin) and spinosad (XDE-105); organophosphate insecticides including acephate, chlorpyrifos, chlorpyrifos-methyl, diazinon, fenamiphos, and malathion; and carbamate insecticides including aldicarb, carbaryl, carbofuran, oxamyl, and thiodicarb.
 16. The method according to claim 15, wherein the agricultural active ingredient is imidacloprid.
 17. The method according to claim 13, wherein the agricultural active is a fungicide selected from the group consisting of tebuconazole, simeconazole, fludioxonil, fluquinconazole, difenoconazole, 4,5-dimethyl-N-(2-propenyl)-2-(trimethylsilyl)-3-thiophenecarboxamide (silthiopham), hexaconazole, etaconazole, propiconazole, triticonazole, flutriafol, epoxiconazole, fenbuconazole, bromuconazole, penconazole, imazalil, tetraconazole, flusilazole, metconazole, diniconazole, myclobutanil, triadimenol, bitertanol, pyremethanil, cyprodinil, tridemorph, fenpropimorph, kresoxim-methyl, azoxystrobin, ZEN90160, fenpiclonil, benalaxyl, furalaxyl, metalaxyl, R-metalaxyl, orfurace, oxadixyl, carboxin, prochloraz, trifulmizole, pyrifenox, acibenzolar-5-methyl, chlorothalonil, cymoaxnil, dimethomorph, famoxadone, quinoxyfen, fenpropidine, spiroxamine, triazoxide, BAS50001F, hymexazole, pencycuron, fenamidone, guazatine, and cyproconazole.
 18. The method according to claim 6, wherein the film substantially covers the surface of the seed.
 19. The method according to claim 15, wherein the step of providing a seed that has been treated with an agricultural active ingredient comprises treating the seed with the agricultural active ingredient.
 20. The method according to claim 19, wherein the step of treating the seed with the agricultural active ingredient comprises contacting the seed with the active prior to applying the film comprising an emulsion of a polymer in water.
 21. The method according to claim 20, wherein the amount of active that is applied to the seed is between about 0.5 gm of active ingredient/100 kg of seed and 1000 gm/100 kg of seed.
 22. The method according to claim 20, wherein the amount of active that is applied to the seed is between about 25 gm of active/100 kg of seed and 600 gm/100 kg of seed.
 23. The method according to claim 22, wherein the amount of active that is applied to the seed is between 50 gm/100 kg of seed and 400 gm/100 kg of seed.
 24. The method according to claim 21, wherein the active is applied to the seed in the form of a liquid suspension.
 25. The method according to claim 24, wherein the active is present in the liquid suspension in the form of particles having an average size of less than about 10 microns.
 26. The method according to claim 25, wherein the active is present in the liquid suspension in the form of particles having an average size of less than about 2 microns.
 27. The method according to claim 25, wherein the active is present in the liquid suspension in a concentration of between about 0.1% and about 50%, by weight.
 28. The method according to claim 27, wherein the active is present in the liquid suspension in a concentration of between about 0.5% and 15%, by weight.
 29. The method according to claim 28, wherein the active is present in the liquid suspension in a concentration of between about 1% and 3%, by weight.
 30. The method according to claim 1, wherein the liquid is non-aqueous.
 31. The method according to claim 1, wherein the liquid is an aqueous/non-aqueous mixture.
 32. The method according to claim 2, wherein the seed is the seed of a plant selected from the group consisting of corn, peanut, canola/rapeseed, soybean, curcubits, cotton, rice, sorghum, sugar beet, wheat, barley, rye, sunflower, tomato, sugarcane, tobacco, oats, vegetables, and leaf crops.
 33. The method according to claim 32, wherein the seed has a transgenic event.
 34. The method according to claim 2, wherein the polymer is selected from the group consisting of polyesters, polycarbonates, co-polymers of styrene, and mixtures thereof.
 35. The method according to claim 2, wherein the polymer is selected from the group consisting of acrylonitrile-butadiene-styrene terpolymer (ABS); ABS modified polyvinylchloride; ABS-polycarbonate blends; acrylic resins and co-polymers: poly(methacrylate), poly(ethylmethacrylate), poly(methylmethacrylate), methylmethacrylate or ethylmethacrylate copolymers with other unsaturated monomers; casein; cellulosic polymers: ethyl cellulose, cellulose acetate, cellulose acetatebutyrate; ethylene vinyl acetate polymers and copolymers; poly(ethylene glycol); poly(vinylpyrrolidone); acetylated mono-, di-, and tri-glycerides; poly(phosphazene); chlorinated natural rubber; polybutadiene; polyurethane; vinylidene chloride polymers and copolymers; styrene-butadiene copolymers; styrene-acrylic copolymers; alkylvinylether polymers and copolymers; cellulose acetate phthalates; epoxies; ethylene copolymers: ethylene-vinyl acetate-methacrylic acid, ethylene-acrylic acid copolymers; methylpentene polymers; modified phenylene oxides; polyamides; melamine formaldehydes; phenolformaldehydes; phenolic resins; poly(orthoesters); poly(cyanoacrylates); polydioxanone; polycarbonates; polyesters; polystyrene; polystyrene copolymers: poly(styrene-co maleic anhydride); urea-formaldehyde; urethanes; vinyl resins: vinyl chloride-vinyl acetate copolymers, polyvinyl chloride and mixtures of two or more of these.
 36. The method according to claim 2, wherein the polymer is biodegradable and is selected from the group consisting of biodegradable polyesters; starch-polyester alloys; starch; starch-PCL blends; polylactic acid (PLA)-starch blends; polylactic acid; poly(lactic acid-glycolic acid) copolymers; PCL; cellulose esters; cellulose acetate butyrate; starch esters; starch ester-aliphatic polyester blends; modified corn starch; polycaprolactone; poly(n-amylmethacrylate); ethyl cellulose; wood rosin; polyanhydrides; polyvinylalcohol (PVOH); polyhydroxybutyrate-valerate (PHBV); biodegradable aliphatic polyesters; polyhydroxybutyrate (PHB), and biodegradable aliphatic polyester (BIONOLLE).
 37. The method according to claim 6, wherein the non-migrating surfactant is selected from the group consisting of diallyl amine pluronics, linoleic alcohol derivatives, allyl alkyl phenol derivatives, acrylate derivatives, allyl alcohol alkenyl succinic anhydride derivatives, maleic derivatives, and Trem LF-40 allyl sulfosuccinate derivatives.
 38. A treated seed that is coated by the method of claim
 1. 39. The seed of claim 38, wherein the seed is a cotton seed or a corn seed.
 40. A method of protection of a seed comprising treating the seed by the method of claim
 1. 